Tsuyoshi Saigō, universally nicknamed "Godzilla" after the Toho monster, embodies a neighborhood menace as a recurring human character. Standing 150 centimeters tall with black eyes, he attends elementary school alongside Shōta Ōhara, Kizao Kiza, and Hakase. His family runs a liquor store, managed by parents Mr. and Mrs. Saigō, and includes an unspecified brother. Academically, he performs poorly.

Godzilla primarily bullies Shōta within class and neighborhood settings, leveraging intimidation tactics. Kizao Kiza typically accompanies him as a lackey, supporting his endeavors while seeking approval. Despite their antagonistic dynamic, underlying care occasionally surfaces, revealing a complex friendship coexisting with rivalry.

He naturally assumes leadership roles in group activities. During a baseball match as captain of school team "G," he initially benches Shōta for perceived inadequacy. Facing a major deficit and depleted morale, he pragmatically recruits both Shōta and Q-Taro. His competitive frustration manifests visibly—like smashing his bat after striking out.

Their rivalry extends beyond bullying into competing for classmate Yoshiko Koizumi's affection. The 1985 anime series adjusted their dynamic for greater balance compared to earlier adaptations, differentiating it from similar relationships in other Fujiko Fujio works.